In general, handover (also known as handoff; hereinafter, referred to as handover) is an important technology for a mobile communication system to switch a radio channel in use. When a user terminal moves to a radio wave arrival range of another wireless base station beyond a radio wave arrival range of one wireless base station, the handover is an operation for transferring the management of the user terminal between the two wireless base stations. Here, the wireless base station is a device that wirelessly communicates with the user terminal and may be referred to by other names. The user terminal may receive a seamless service even when moving from a serving wireless base station to another wireless base station through the handover.
To successfully perform the above-described handover, information regarding a neighboring base station should be possessed.
Conventionally, the handover may be based on the reception level and quality of a serving base station and the transmission power and level measured in the serving base station and may use the reception level reported from a cell of a neighboring base station along therewith.
In measured information of neighboring base stations, only a base station identity code (BSIC), that is, base station information, and an average value of reception levels measured during a measurement period may be reported.
Four factors—the reception power, the reception quality, the transmission power, and the transmission quality—may be used with respect to the serving base station, but only the reception level may be measured with respect to the neighboring base station. Since quality information may not be used with respect to the neighboring base station, there is a problem in that the handover should be performed again due to actual low quality in a cell of a target base station even when the handover to the target base station is actually performed, or the handover may fail and a return to a previous channel may be disabled due to the steep degradation of quality.